Results 111 to 120 of about 32,483 (245)

The Detectability of CH4/CO2/CO and N2O Biosignatures Through Reflection Spectroscopy of Terrestrial Exoplanets

open access: yesThe Astronomical Journal
The chemical makeup of Earth’s atmosphere during the Archean (4–2.5 Ga) and Proterozoic eon (2.5–0.5 Ga) contrast considerably with the present-day: the Archean was rich in carbon dioxide and methane, and the Proterozoic had potentially higher amounts of
Armen Tokadjian, Renyu Hu, Mario Damiano
doaj   +1 more source

Dating the cyanobacterial ancestor of the chloroplast [PDF]

open access: yes, 2009
Cyanobacteria have played a pivotal role in the history of life on Earth being the first organism to carry out oxygenic photosynthesis, which changed atmospheric chemistry and allowed the evolution of Eukarya.
Amanda Castillo   +2 more
core   +1 more source

Ediacara Obscura: Unveiling Hidden Magnetisations in the Fen Complex, Southern Norway

open access: yesGeochemistry, Geophysics, Geosystems, Volume 27, Issue 5, May 2026.
Abstract Paleomagnetic directions found in Ediacaran (635–539 Ma) rocks are widely dispersed, which has led to conflicting hypotheses about tectonic regimes and geomagnetic field behavior during this period, and raised doubts about the fidelity of the paleomagnetic record.
Justin A. D. Tonti‐Filippini   +8 more
wiley   +1 more source

Secular Changes in the Occurrence of Subduction During the Archean

open access: yesGeophysical Research Letters
Subduction processes play a pivotal role in facilitating material exchange between the crust and mantle, contributing to the growth of continents. However, the onset and evolution of subduction remain hotly debated.
Chun‐Tao Liu   +2 more
doaj   +1 more source

Quantitative study on vertical distribution of heat flow in Niutuozhen geothermal field, Xiong'an New Area—Evidence from heat flow determination in the Archean of D01 well

open access: yesJournal of Groundwater Science and Engineering
The karst geothermal reservoir in Xiong'an New Area is a representative example of an ancient buried hill geothermal system. However, published heat flow data are predominantly derived from the Cenozoic sedimentary cap.
Ya-hui Yao   +7 more
doaj   +1 more source

Workshop on the Early Earth: The Interval from Accretion to the Older Archean [PDF]

open access: yes
Presentation abstracts are compiled which address various issues in Earth developmental processes in the first one hundred million years. The session topics included: accretion of the Earth (processes accompanying immediately following the accretion ...
Ashwal, L. D., Burke, K.
core   +1 more source

Chemical Geodynamics of Granitoid Magmatism During a Pacific‐Philippine Sea Plate Transition in Southwest Japan

open access: yesGeochemistry, Geophysics, Geosystems, Volume 27, Issue 5, May 2026.
Abstract Granitoid magmatism along the western Pacific margin records interactions between subduction dynamics and crust–mantle processes; however, the links between plate reorganization and magma‐source evolution remain debated. Here we integrate U–Pb zircon geochronology with Pb–Sr–Nd–Hf isotope systematics to investigate Cretaceous–Paleogene ...
Nghiem V. Dao   +7 more
wiley   +1 more source

Data‐Driven Investigation Reveals Subaerial Proportion of Basalts Since the Early Archean

open access: yesGeophysical Research Letters
The subaerial exposure of the modern continental crust through time remains intensely debated, with estimates of the first exposure ranging from the late Archean to the Neoproterozoic.
Chun‐Tao Liu   +2 more
doaj   +1 more source

Was H2O2 generated before oxygenic photosynthesis?

open access: yesRedox Biology
We obviously agree with Wu et al. that H2O2 might accumulate in the Archean land waters devoid of Fe2+. We do disagree on the topic of the half-life of H2O2, as the work cited in support for a longer half-live is not relevant to the conditions in the ...
Willem H. Koppenol, Helmut Sies
doaj   +1 more source

Timing of Metamorphism and Deformation in the Neoarchean Quetico Metasedimentary Belt, Superior Craton, Constrained by Garnet Trace‐Element Mapping and Lu–Hf Geochronology

open access: yesJournal of Metamorphic Geology, Volume 44, Issue 4, Page 265-286, May 2026.
ABSTRACT The Quetico subprovince of the Superior Province is among the largest metasedimentary belts globally and provides evidence of tectonic processes at play during the final stages of Archean cratonization. Although previous studies have shown that deformation and metamorphism of the 2.7‐Ga turbiditic protolith resulted in regional subvertical ...
Adrian G. Rehm   +4 more
wiley   +1 more source

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